The invention relates to a gearshift fork activation device for optionally activating at least two gearshift forks of a gearbox, having a blocking device for blocking a gearshift fork which is not to be activated and having a driver for driving a gearshift fork, to be activated, in an axial direction.
Such devices are usually components of a rotational speed torque converter, in particular of a two-stage gearwheel speed transforming gearbox for motor vehicles. A change of gear speed or transmission ratio of such a speed transforming gearbox, which is used as a main gearbox, is activated by two mechanical input signals. One input signal is generated by the selection direction of the gearshift lever. In this context, it is necessary to decide which of the gearshift forks available for selection is to be activated. The second input signal is generated by the shifting direction of the gearshift lever. For example, the gearshift fork can be moved in the shifting direction between two shifted positions and a neutral position. The shifting direction and selection direction are usually transmitted as mechanical signals to the gearbox via a Bowden cable or a linkage. These two mechanical input signals are used at the input of the transmission for selecting the gearshift fork to be activated and for moving the selected gearshift fork between the corresponding positions using the driver. In a three-gear-speed main gearbox with a reverse gear speed, for example, these two mechanical input signals are transmitted to two gearshift forks, which can each assume two shifted positions and one neutral position. During the selection and the subsequent activation of the gearshift fork it is necessary to ensure that the gearshift forks move only in accordance with a predefined shifting scheme and no inadmissible states can be set. For example, two gearshift forks must not be in engagement at the same time.
According to the prior art, the selection movement of the gearshift lever is converted at the gearbox into, for example, a linear movement of a shifting finger in order to select a gearshift lineal. In this context, the gearshift finger slides on a linkage in a transverse movement with respect to the longitudinal axis of the gearshift lineal in a gearshift gate, which is formed by recesses in the gearshift lineals that are oriented in parallel. The shifting movement, that is to say the activation of a gearshift lineal which has a gearshift fork, can, for example, be converted into a rotational movement of the gearshift finger, which then moves the gearshift fork over the selected gearshift lineal along the longitudinal axis of the gearshift lineal and thus engages parts of the gearbox in the force flux or disengages them from it.
In the case of partially automated or fully automated change speed gearboxes, it is possible for the mechanical input signals (the shifting direction and the selection direction) also to be supported or converted by use of electromotive, pneumatic or hydraulic actuation means, and for the gearbox to be controlled in this way.
While the gearbox is being operated, it is necessary always to ensure that the gearshift forks, or the gearshift lineals which are associated therewith, move only according to the predefined shifting scheme (for example, an H shifting pattern) during selection and gear shifting processes and no inadmissible states, for example also those due to vibrations, can be set. In particular, it is necessary to avoid two gearshift forks being able to be placed in engagement simultaneously to gearbox parts.
Gearboxes according to the prior art have the disadvantage that the gearshift lineals and the gearshift forks attached thereto and the control unit which activates the gearshift lineals are complex to mount. Furthermore, such control units often have a very complicated design.
The invention is consequently based on the object of developing a gearshift fork activation device for a gearbox in such a way that the above mentioned disadvantages are avoided. The intention is, in particular, that such a gearshift fork activation device will have a simple design with very few components.
The gearshift fork activation device according to the invention includes a bearing axle, which is arranged in the axial direction and which supports at least one blocking part of the blocking device and at least one driver part of the driver. The support of a blocking part and of a driver part on a bearing axle, which extends in the axial direction, ensures that, on the one hand, the mounting of the gearshift fork activation device can be carried out essentially independently of the remaining parts of the gearbox in terms of the selecting, shifting and blocking functions of the gearshift fork activation device. On the other hand, in a further step the functionality of the gearshift activation device is likewise checked independently of that of the gearbox. Together these produce significant progress in terms of safety-optimized and productivity-optimized production of change speed gearboxes. Furthermore, the arrangement of the blocking part and of the driver part on the axially arranged bearing axle permits a considerable reduction in components while maintaining the same functionality, and a reduced probability of failure is also implemented. In particular, a short distance between the blocking parts and driver parts such as, for example, gearshift rods and parts of the gearbox associated therewith, for example, gearwheels, can be implemented. This permits a short design of the corresponding gearshift forks. Finally, this arrangement permits the activation of the bearing axle, which supports the blocking part and the driver part, to be advantageously facilitated by a booster unit or for it to be entirely or partially automated by use of suitable actuator elements.
In one advantageous embodiment, there is provision for the bearing axle to be formed by a piston rod, in particular by a piston rod of a servo cylinder. In this way, it is possible for the force transmitting unit, in particular the servo cylinder, to activate directly the bearing axle which is embodied as a piston rod, and thus support disengagement or engagement of gearbox parts into the force flux, and in particular also to carry this out automatically. The mounting and the checking can also be performed independently of the actual gearbox here.
In particular, it is advantageously possible to provide for the driver part to be arranged so as to be displaceable in the axial direction. The driver part can thus drive the gearshift fork, to be activated, in the axial direction along the bearing axle and thus shift parts of the gearbox.
In a further advantageous embodiment, the bearing axle supports the driver part in such a way that it can carry out a rotational movement about the axial direction. In this way, the selection of a gearshift fork to be activated can thus be made possible by the rotational movement of the driver part, for example.
One preferred further development of the invention provides for the driver part to have an external circumferential section with a first control contour, which is provided for interacting with circumferential contours of at least two gearshift fork rods that support the at least two gearshift forks. Through a corresponding embodiment of the first control contour and of the circumferential contours of the gearshift fork rods with which the first control contour of the driver part interacts, it is thus possible to drive a gearshift fork, to be activated, in an axial direction. By correspondingly changing the position of the driver part, it is possible to select the gearshift forks to be activated and drive them while other gearshift forks, which are not to be activated, can be released.
Furthermore, there is advantageously provision for the first control contour to drive the gearshift fork to be activated in the axial direction and at the same time not act on the gearshift fork which is not to be activated. When there is a change in position of the driver part, the first control contour interacts with the circumferential contour of the gearshift fork which is to be activated and at the same time does not interact with the circumferential contour of the second gearshift fork which is not to be activated, by virtue of a corresponding configuration of the first control contour and of the circumferential contours of the gearshift fork rods which are to be activated. In this way, the gearshift fork which is to be activated is selected and can be slid in the axial direction.
Furthermore, in one preferred embodiment, there is provision for the blocking part to be secured in the axial direction. This brings about blocking of the gearshift fork, which is not to be activated, in the axial direction and thus easily prevents undesired engagement or disengagement of gearbox parts when the blocking part interacts with a gearshift fork which is not to be activated.
Furthermore, it is possible to provide for the bearing axle to support the blocking part in such a way that it can carry out a rotational movement about the axial direction. Such a rotational movement allows the blocking part to interact with the gearshift fork which is to be activated and thus block sliding of the gearshift fork to be activated in the axial direction.
In particular, it is possible for one advantageous embodiment to provide for the blocking part to have an external circumferential section with a second control contour, which is provided for interacting with circumferential contours of at least two gearshift fork rods that support the at least two gearshift forks. In this way, the blocking part can interact, by way of the second control contour with the circumferential contour of a gearshift fork rod which has a gearshift fork which is not intended to be activated. A suitable rotation of the blocking part can thus control the freedom of movement of the gearshift fork which is not to be activated.
In preferred embodiments of the device according to the invention, there is also provision for the second control contour to block a movement of the gearshift fork, which is not to be activated, in the axial direction and at the same time release a movement of the gearshift fork, which is to be activated, in the axial direction. This blocking interaction of the second control contour with a gearshift fork, which is not to be activated, and the simultaneous release of a gearshift fork, which is to be activated, controls the axial movements of the gearshift fork by way of a single control movement. This permits a considerable reduction in the number of components to be used, and thus also provides a significant cost saving.
A further advantageous embodiment is obtained by virtue of the fact that a rotational movement of the blocking part about the axial direction is coupled to a rotational movement of the driver part about the axial direction. The coupling, in particular the synchronization of the rotational movements of the blocking part and of the driver part about the axial direction, in this way brings about, given a suitable rotational movement, release of the gearshift fork which is to be activated and blocking of the gearshift fork which is not to be activated. At the same time, it brings about interaction between the driver part and the gearshift fork which is to be activated, so that during a subsequent movement of the driver part, which takes place in the axial direction, the gearshift fork which is to be activated is driven in the axial direction, while at the same time the blocking part of the blocking device blocks the gearshift fork, which is not to be activated, in the axial direction. This coupling of the movements reduces the expenditure on controlling the gearbox.
Furthermore, in one advantageous embodiment there is provision for the driver part and the blocking part to be arranged coaxially. A coaxial arrangement of the driver part and of the blocking part on the bearing axis, which extends in the axial direction, permits, for example, a synchronous movement of the driver part and of the blocking part and, furthermore, permits a relative movement of the drive part and blocking part in the axial direction. This permits simple and cost-effective simultaneous control of the driver part and blocking part.
Likewise, in one embodiment there is advantageous provision for the driver part to have at least one groove. One or more such grooves can interact with corresponding pins or webs in, for example, one section of a housing. This permits the movements of the driver to be controlled. For example, activation of a gearshift fork is ensured only within a predefined shifting scheme.
The invention furthermore relates to a gearbox, in particular for motor vehicles, having a gearshift fork activation device according to the invention.
In such a gearbox it is possible, in particular, to provide for such gearbox to be a manual or partially automatic change speed gearbox. For example, the gearshift fork activation device according to the invention may be configured for a manual change speed gearbox with Bowden cable activation.
The invention provides for common mounting of the blocking part and driver part on an axially arranged bearing axle, which makes available a modular gearbox control unit. The modular gearbox control unit can be premounted and checked together with the gearshift forks. The finished unit can then be installed in the gearbox casing. Furthermore, in this way it is possible to implement a simple design with very few components, which design has a small installation space and in which gearshift forks which are not used can be blocked mechanically. Furthermore, the entire shifting and selection mechanism can be mounted on a booster unit such as, for example, a servo cylinder.
Other objects, advantages and novel features of the present invention will become apparent from the following detailed description of the invention when considered in conjunction with the accompanying drawings.